October 2014 – Organic Olive Oil Farming and the Farm Experience with Michael O’Brien of Paso Gold

Michael O'Brien, organic olive oil farmer and owner of Paso Gold.

Michael O’Brien, organic olive oil farmer and owner of Paso Gold.

Did you know that all olives in the Northern Hemisphere are harvested in November and December? The next time you pick up a bottle of American or European olive oil, note the harvest date rather than the “best by” date. This was one among many nuggets of wisdom from our guest speaker, organic olive oil farmer Michael O’Brien of Paso Gold. After generously treating us to an enormous salad of roasted San Marzano tomatoes and Persian cucumbers from his farm, Michael shared his story and gave us an insider’s look at the olive oil industry.

The farm experience can be life-saving

Before he started farming, Michael worked as a mechanic at American Airlines for 36 years, as well as a tuna-spotting pilot part-time. Ten years ago, he began asking, “What can I do in my life that won’t earn me a death certificate?”

An investigation into healthy eating led him to the Mediterranean diet, where he was struck by the key component of olive oil. Research was coming out that showed how olive oil helps reduce Alzheimer’s disease and raises good cholesterol.

He bought some land in Paso Robles, California and looked into suitable crops. It turned out he had too much land for carrots and not enough land for pistachios. He decided on olives and designed his farm to support a Mediterranean lifestyle, choosing quality over profit at every turn.

The 9.1-acre farm is home to wildlife including quail, rabbits, deer, baby owls, and hummingbirds. A family of tarantulas lives peacefully on the farmhouse. Michael also plants vegetables such as Persian cucumbers and San Marzano tomatoes, enjoying a bountiful personal fall harvest.

The farm is currently on sale due to family reasons, but Michael plans to continue growing tomatoes and cucumbers in Southern California.

Michael's presentation was extremely informative and eye-opening.

Michael’s presentation was extremely informative and eye-opening.

Uncompromising quality practices

As a small operation, Paso Gold can focus on industry best practices to deliver truly exceptional organic olive oil. Indeed, it often exceeds even strict California standards.

To water the olive trees, Paso Gold employs auto-drip irrigation which provides superior control of water usage. Michael logs all water usage, which is typically 2.5 gallons per hour per tree. Running water pumps at night and using gravity feeds during the day conserve electricity.

During harvest, Michael hires workers to hand-harvest the olives to preserve tree health. The workers wear a basket and comb the olives into the basket with their hands. By picking the olives green, Michael sacrifices yield in favor of higher polyphenol and antioxidant content.

In contrast, over-the-row harvesting is done by machines that rip branches off. The resulting damage requires a non-organic copper spray on the trees to prevent bacterial infection. Olives start to ferment the minute they are picked, but over-the-row harvesting bruises the fruit and causes them to ferment more quickly.

While one ton of dark olives yield approximately 40 to 50 gallons of oil, green olives yield 15 to 20 gallons. There is quite a difference in letting them go longer. In larger olives, some antioxidants are lost due to higher water content causing them to leech from the oil into the water.

In order to preserve nutrients, transporting the olives to the mill in timely manner is very important. It is good practice to transport the olives to the mill within 8 hours of picking. Paso Gold’s mill is only 2 miles down the road from the olive trees, so his olives are typically milled 2.5 hours after picking.

Some of Paso Gold’s olive trees are near non-organic vineyards, but Michael uses the National Organic Program’s notification statutes to protect his crop. Under the protocol, any neighbors who have non-organic vineyards must notify him when they are spraying and park a car on the service road between the farms. If any spray gets on the car’s windshield, they must buy his crop.

As one of the few farmers who personally sells his olive oil at farmers markets, Michael caught the notice of David Karp of the LA Times. Michael is featured in Karp’s LA Times article on the recent California olive oil boom.

Our chapter was treated to an olive oil tasting of two different blends accompanied with roasted San Marzano tomatoes also from Michael's farm.

Our chapter was treated to an olive oil tasting of two different blends accompanied with roasted San Marzano tomatoes also grown on Michael’s farm.

Modern olive oil extraction

In the old days, they pressed olives with stones, which gave birth to the term “cold pressed,” although their method had sanitation issues. Today, olives are washed and then ground up, including the pit which contains 22% of the oil; nothing is wasted.

In the first step, the olives are crushed to a fine paste by hammer crusher, disc crusher, depitting machine, or knife crusher. Then, the paste is malaxed (kneaded) for 30 to 60 minutes in order to allow the small olive droplets to agglomerate. Aromas are created in these two steps through the action of fruit enzymes.

Afterwards, the paste is pumped into a horizontal centrifuge where the phases are separated by a large capacity industrial decanter rotating at about 3,000 rpm. The high centrifugal force separates all the phases according to their densities: solids (pomace), vegetation water, and oil. For fine-tuning, a vertical centrifuge working at around 6,000 rpm spins out the last bit of water.

Oil right out of the spigot must sit in barrels for 30 to 60 days before bottling to allow the last of the vegetation water to evaporate and any solids to sink. Otherwise, the vegetation water allows bacterial growth and leads to rancidity. Finely filtering olive oil is not necessary as long as the sediment is allowed to settle.

During bottling, Michael uses argon to purge out the oxygen so the olive oil will not oxidize before opening.

We couldn’t get enough of the delicious olive oil.

Olive oil is a tough business

Low yield is a very real problem for olive farmers and depends on many factors. Yield is determined by the oil content of the fruit, extractability of the oil, and the extraction process. Yield per acre can range from less than one to as high as 9 tons per acre. Paso Gold shoots for a consistent yield from year to year of about 4 tons per acre.

Low yield usually can be related back to a lack of shoot growth the previous year from poor tree vigor. For example, 100 of Michael’s arbequina olive trees froze when temperatures plummeted to 15 °F. He had to take three months off of market to prune the trees back. Considering the drought, the freeze, and the pruning, he elected not to have a crop this year, making November 2013 his last crop.

Other causes of low yield are poor weather conditions during bloom, lack of chilling, frost damage, or inadequate flower pollination. Olives are strongly alternate bearing, so a low crop yield one year will likely promote more shoot growth, resulting in more flowers and higher yields the following year. However, the alternate bearing aspect also makes for unpredictable production, which is why the California olive industry has shrunk in recent years.

Paso Gold's arbosana olives, hand-harvested and milled within 8 hours.

Paso Gold’s arbosana olives, hand-harvested and milled within 8 hours.

Is your olive oil extra virgin? What to look for

Unfortunately, mass production of olive oil has led to some practices that are less than ideal. A comprehensive UC Davis report found that over 90 percent of typical olive oil sold in California was adulterated with other oils. One way that producers cut corners is by mixing cold-pressed oil with refined oil. After the olives are first cold-pressed, they heat the leftover paste into nutritionally worthless refined oil and mix it with the cold-pressed oil to increase volume.

The best way to know if your olive oil is truly extra virgin is to know your farmer and ask for lab results for polyphenols, oleic acid, and peroxide. Michael gladly shares his lab results with the public, and he shared his recent polyphenol and oleic acid results with us.


Polyphenols, the antioxidants in oleic acid, are considered “high” by the USDA if over 150 mg/kg. Michael’s last crop tested at 212mg/kg of polyphenols, well exceeding the USDA standards. He attributes these results to his practice of picking the olives when green.

Oleic Acid and Peroxide

Oleic acid marks the difference between virgin and extra virgin olive oil. The percentage of oleic acid reflects all farming practices, from growing and harvesting to milling and storage. The smaller the percentage of oleic acid contained in the free fatty acids, the better. The USDA oleic acid standard is 0.80% or lower, and the California Olive Oil Council (COOC) standard is 0.50% or lower.

Peroxide value reflects the amount of free-floating oxygen molecules and indicates rancidity level. The USDA peroxide value standard is 20 meq/kg or lower, and the COOC standard is 15 meq/kg or lower.

For his oleic acid and peroxide tests, Michael tried an experiment where he left a half-used bottle open for six months. He used that oil for the test. Despite being open for six months, the Paso Blend oil tested at 0.12% oleic acid and 11 for peroxide value, far superior to both the USDA and COOC standards.


Oleocanthanol, one of the antioxidants in olive oil, has anti-inflammatory qualities similar to non-steroidal anti-inflammatory drugs (NSAIDs). A 2005 study found that taking 50g (>3.5 tsp) of typical extra virgin olive oil per day has similar anti-inflammatory effect as 1/10 of adult dose of ibuprofen.

Also, oleocanthanol is responsible for the spicy feeling in the back of your throat. Olive oil that does not produce the peppery, tickling sensation in the throat has likely had its antioxidant level hurt by sunlight beating on store shelves or cooked out by the industrial process.

Farmers market tips

Did you know there are certified and non-certified sections in farmers markets? Sellers in the certified section grow their produce themselves. Non-certified sellers can sell produce from any third party, even if the produce was conventionally grown.

Only the certified section requires an actual “farmer on duty.” The San Francisco Ferry Building farmers market is one of the few that requires farmers to be on duty.

Though he won't have olive oil next year, Michael will have San Marzano tomatoes and Persian cucumbers.

Though he won’t have olive oil next year, Michael will have San Marzano tomatoes and Persian cucumbers.

Making the most of your olive oil

Do you avoid cooking with extra virgin olive oil because you’ve heard it has a low smoke point? Actually, the smoke point of olive oil is quite high, around 300 °C. UC Davis has yet to come out with an official number, but their current answer is not to heat olive oil for more than 30 minutes.

The reason we are advised not to cook with olive oil is due to the other oils mixed in during the industrial process — those are the oils that are smoking. The presence of impure oils misleads people to think the olive oil is smoking.

The perfect temperature for storage is 57.3 °F. The shelf life of high-quality “tree to bottle” olive oil is around 2 years if kept at 70-75 °F. If opened, it will most likely last one year. What if you were take oil stored in your kitchen at 70 °F and heat it for 10 minutes at 100 °F? We do not yet have a straight answer from UC Davis.

What about refrigerating your olive oil as a test of purity? You’ve probably heard the theory: If it is pure extra virgin olive oil, it should coagulate into a buttery texture. Michael’s advice: The fridge test will verify real olive oil, but also ruin it. Coagulation destroys the flavor and the low temperature causes condensation which invites bacteria to grow in the water. If you’re really curious, pour some into a little cup and refrigerate that. By next morning, it should be like butter.

How do you know when your oil is rancid? It will smell waxy and cause a bad burning.

Bottom line: There is no need to refrigerate extra virgin olive oil. As long as you have good quality “tree to bottle” oil with a two-year shelf life and keep it covered away from the stove at around 70 to 75 °F, you will finish using it before any ill effects.

Where to find Paso Gold

Michael is selling the last of his olive oil at the Pasadena Victory Park farmers market. He usually sells out by the end of the year, so act fast! For more great info on olive oil, check out his website. The slideshow from his presentation can be downloaded here.

Any other comments or questions about olive oil? Leave a comment below!

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